Understanding the molecular events controlling the development of the embryonic vasculature has the promise of providing a variety of therapeutic tools useful in clinical settings aimed at regulating vessel growth. These opportunities include the repair of damaged vessels in conditions of inflammation, the stimulation of vessel growth following ischaemic injury, and the repression of vasculogenesis/angiogenesis to block the growth of tumors. This proposal aims at understanding the role(s) that two members of the GATA family of transcription factors, GATA4 and -6, play in the development of the embryonic vascular system.